Version control for .blend files
At the Blender Institute / Blender Animation Studio we use Subversion for our projects. It works fine for blend files, but you have to make sure they are not compressed. Compression can cause the entire file to be different when only a single byte changed, whereas in the uncompressed blend file only that one byte will differ. As a result, binary diffs will be much smaller, and your repository will be faster to work with.